This invention relates to an extension jib attached to a boom, such as a telescopic boom.
An extension jib is attached to a tip of a telescopic boom of a crane such as a hydraulic truck crane, a rough terrain crane and others, in order to extend the available length of the boom. The extension jib is turned to a retracted waiting position on a side of the boom when it is not used.
In a prior art, the extension jib is moved between the extended position and the retracted position in a large space, as described later on.